Conventionally known polyphenol derivatives include catechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, and gallocatechin gallate contained in tea leaves, which have been used as physiologically functional substances exhibiting various physiological activities.
Moreover, it has also been proposed that a post-fermented tea leaf containing 4-ethenyl-1,2-dimethoxybenzene, aceteugenol, or isoeugenol is produced by fermenting a tea leaf with a microbe PK-1 belonging to the genus Aspergillus (FERM P-21280) or a microbe KA-1 belonging to the genus Eurotium (FERM P-21291) (Japanese Patent Laid-Open No. 2008-263831).    Patent Literature 1: Japanese Patent Laid-Open No. 2008-263831